Caption: Medieval alchemy. Three medieval illustrations of alchemists using distillation apparatus. In all three images the master alchemist is sitting in a chair and directing an apprentice who is actually operating the distilleries. He is using fire to heat mixtures of substances contained in the vessels on top of the distilleries. Distilla- tion separates mixtures into its separate compon- ents by boiling off the most volatile chemicals present. These chemical vapours may be condensed and collected by passing them through a cool tube; these tubes are seen here projecting from the sides of the vessels. Image from the 14th century.